440 . Mr: Fox on the Temperature of Mines: [Dec 
glass was heated, I forced the mercury from the bulb with the 
heat of my hand past, the heated spot: the heat was great, 
though not visible, and as the mercury rose in a gaseous state, 
and passed to the upper end.of the tube where it was condensed, 
I was struck with the phenomenon of a vivid flash of light (par- 
ticularly observable in the dark) of a bright blue colour. This 
continued so long as the heat was sufficient to raise the mercury 
to a gaseous state. p Pi. 
* This light much resembled the electrical spiral tube, and a 
frequent repetition of the experiment was uniformly attended 
with similar results. I now admitted the air, and the same 
effects could not be produced. On using a tube of larger dimen- 
sions, and under similar circumstances, the effect was much 
more striking. 
I at first suspected that possibly the mercury might be conta- 
minated with a small portion of zinc, as the brilliant light so much 
resembled that metal in a state of ignition; but on ‘repeating 
the experiment with mercury in which no trace of any adventi- 
tious ingredient could be discovered, the effects. were precisely 
as before. I am, Sir, your obedient servant, ) 
. M. P. Moytz, 
(oS ee 
ArticLe’ VI. 
On the Temperature of Mines. Communicated to the Cornwall 
Geological Society, by R. W. Fox, Esq. 
Tue high temperature which prevails in mines having excited 
some attention, 1 am induced to submit to the Cornwall Geologi- 
cal Society the result of further observations which have been 
made on the subject in several mines, since my last communi- 
cation. , 
At South Huel Towan copper mine, in the parish of St. Agnes, 
the temperature of the water in the cistern at the “ sump,” or 
bottom of the mine (45 fathoms deep), was 60°. This may be 
taken, therefore, as the mean temperature of the streams of 
water, which flow through the deepest levels, or galleries, into 
the cistern, Two men were employed at one time (that is, 8 in 
24 hours) in this part of the mine. i 
East Liscomb, a copper mine in Devonshire, depth 82 fathoms, 
Temperature of water in the cistern 64°. 
_ Huel Unity Wood,.a tin and copper mine in Gwennap Parish, 
depth 86 fathoms. Temperature of water, taken as before, 64°. 
Four men constantly worked at the bottom of this mine, 
Beer Alston, a lead mine in Devonshire, 120 fathoms deep ; 
water 66:5° of temperature, taken as before. . 
